BACKGROUND:Hypertension is one of the most prevalent chronic non-communicable diseases and affects more than 60% of individuals over 60 years of age. Additionally, hypertension is a prominent risk factor for the development of cardiovascular diseases (CVDs). Human body composition is both the result and predictor of an individual's health status, and hypertension has consistently been shown to be more prevalent among obese individuals. In the current study, we focussed on the association between body composition parameters and hypertension occurrence. METHODS:Data from KardioVize 2030, a population-based study (n = 1988), was used to determine the association between the body composition parameters related to both fat and water content with hypertension. Body composition was assessed using the direct segmental multi-frequency bioelectrical impedance analysis method (DSM-BIA). RESULTS:Using logistic regression modelling we found that the majority of hypertension incidence could be determined by body fat and water content, as hypertension occurrence was positively correlated with increased fat-related body composition parameters and water content. Specifically, results from this study demonstrate that increased intracellular fluid was positively associated with higher hypertension incidence in men (14%) and women (16%). CONCLUSION:Body composition reflects the occurrence of hypertension and may serve as a novel therapeutic goal that can be easily implemented in the clinical setting using DSM-BIA.

Aims Patients with non-ischemic dilated cardiomyopathy (DCM) are at considerable risk for end-stage heart failure (HF), requiring close monitoring to identify early signs of disease. We aimed to develop a model to predict the 5-years risk of end-stage HF, allowing for tailored patient monitoring and management. Methods and results Derivation data were available from a Dutch cohort of 293 DCM patients, with external validation available from a Czech Republic cohort of 235 DCM patients. Candidate predictors spanned patient and family histories, ECG and echocardiogram measurements, and biochemistry. End-stage HF was defined as a composite of death, heart transplantation, or implantation of a ventricular assist device. Lasso and sigmoid kernel support vector machine (SVM) algorithms were trained using cross-validation. During follow-up 65 (22%) of Dutch DCM patients developed end-stage HF, with 27 (11%) cases in the Czech cohort. Out of the two considered models, the lasso model (retaining NYHA class, heart rate, systolic blood pressure, height, R-axis, and TAPSE as predictors) reached the highest discriminative performance (testing c-statistic of 0.85, 95%CI 0.58; 0.94), which was confirmed in the external validation cohort (c-statistic of 0.75, 95%CI 0.61; 0.82), compared to a c-statistic of 0.69 for the MAGGIC score. Both the MAGGIC score and the DCM-PROGRESS model slightly over-estimated the true risk, but were otherwise appropriately calibrated. Conclusion We developed a highly discriminative risk-prediction model for end-stage HF in DCM patients. The model was validated in two countries, suggesting the model can meaningfully improve clinical decision-making.

Pulse wave velocity is a commonly used parameter for evaluating arterial stiffness and the overall condition of the cardiovascular system. The main goal of this study was to establish a methodology to test and validate multichannel bioimpedance as a suitable method for whole-body evaluations of pulse waves. We set the proximal location over the left carotid artery and eight distal locations on both the upper and lower limbs. In this way, it was possible to simultaneously evaluate pulse wave velocity (PWV) in the upper and lower limbs and in the limbs via four extra PWV measurements. Data were acquired from a statistical group of 220 healthy subjects who were divided into three age groups. The data were then analysed. We found a significant dependency of aortic PWV on age in those values measured using the left carotid as the proximal. PWV values in the upper and lower limbs were found to have no significant dependency on age. In addition, the PWV in the left femoral artery shows comparable values to published already carotid-femoral values. Those findings prove the reliability of whole-body multichannel bioimpedance for pulse wave velocity evaluation and provide reference values for whole-body PWV measurement.

The main goal of this study was to make a comparison of aortic flow timing obtained by PW Doppler in four aortic sections with timing of − dZ/dt max obtained by bioimpedance measurement in nine locations on the thorax and neck. This knowledge is essential for determination of which bioimpedance channel could be used as a proximal for evaluation of pulse wave velocity (PWV) from the beginning of the ascending aorta or another aortic section. Time intervals between the Doppler flow and bioimpedance information (− dZ/dt max) were compared. It was found that the channel located on the left part of the neck is the most suitable as a proximal bioimpedance channel which corresponds to the aortic arch. This match is obtained with regard to the value of the time difference as well as inter-subject stability. This channel can be used as a proximal for evaluation of pulse wave velocity from the aortic arch to the desired distal target place in the body when distance between measured parts is known. The data from 35 volunteers with adequate signal quality were analyzed.

The cardiovascular system is described by parameters including blood flow, blood distribution, blood pressure, heart rate and pulse wave velocity. Dynamic changes and mutual interactions of these parameters are important for understanding the physiological mechanisms in the cardiovascular system. The main objective of this study is to introduce a new technique based on parallel continuous bioimpedance measurements on different parts of the body along with continuous blood pressure, ECG and heart sound measurement during deep and spontaneous breathing to describe interactions of cardiovascular parameters. Our analysis of 30 healthy young adults shows surprisingly strong deep-breathing linkage of blood distribution in the legs, arms, neck and thorax. We also show that pulse wave velocity is affected by deep breathing differently in the abdominal aorta and extremities. Spontaneous breathing does not induce significant changes in cardiovascular parameters.

Background: Cardiovascular diseases are the leading causes of mortality and morbidity in modern society. The autonomic nervous systems innervate blood vessel walls and regulate contraction and wall tension. The head-up tilt test is frequently performed for evaluating sympathetic nervous system function. The filling of the lower extremities during the head-up tilt test is measured by the bioimpedance method. Increased blood volume in the area of interest increases the electrical impedance of this area. Methods: We used a mathematical fitting model to express the measured data. A B time constant of a decreased bioimpedance signal during a head-up tilt was calculated for the right leg during various time intervals of tilt duration. We optimized the duration in a study protocol based on corresponding measured data and a calculated model. A group of 22 healthy volunteers (11 men and 11 women) participated in the study protocol: the protocol included a 2-minute supine position and 5-minute head-up tilt test. Results: According to the Mann-Whitney test, there were no statistical differences in the B constant between the groups of men and women. Our results showed the optimal time duration of the head-up tilt test to be about 270 s. Conclusions: Calculating the time constant for decreased bioimpedance during a head-up tilt test might lead to a simple pre-diagnostic method for performing a non-invasive evaluation of the cardiovascular system.

The aim of this proof-of-concept study is to introduce new high-dynamic ECG technique with potential to detect temporal-spatial distribution of ventricular electrical depolarization and to assess the level of ventricular dyssynchrony.

The design, properties, and possible diagnostic contribution of a multichannel bioimpedance monitor (MBM) with three independent current sources are presented in this paper. The simultaneous measurement of bioimpedance at 18 locations (the main part of the body, legs, arms, and neck) provides completely new information, on the basis of which more precise haemodynamic parameters can be obtained. The application of the MBM during various haemodynamic stages, such as resting in a supine position, tilting, exercise stress, and various respiration manoeuvres, is demonstrated. Statistical analysis on a group of 34 healthy volunteers is presented for demonstration of blood flow monitoring by using the proposed method.

With increasing age, the cardiovascular system loses its efficiency. The goal of this work was to investigate the hemodynamic system response to a head-up tilt test in two groups of different aged people. We used a model for describing this response in the right calf based on a non-invasive, non-occlusive, bioimpedance signal measurement technique. A decrease in the bioimpedance value in the calf during the head-up tilt test is associated with the accumulation of blood in the calf, which can be expressed by a model parameter. Subjects were examined in both a head-up tilt test and a supine position. 50 healthy non-smoking volunteers were divided into two groups according to age. The impedance signal during the tilt test for each subject was fitted by a model exponential function: Z 0 model EF (t) =A∗exp(−t/B)+C, where Z 0 model EF (t) is the calculated model of electrical impedance in the calf by an exponential function, A is the amplitude of impedance change, B is the time constant of the impedance decrease, C is the value of the steady state after the tilt test and t denotes time. A lower time constant B shows a faster filling of the vascular system in the investigated part. The Mann-Whitney test (p-value<0.005) revealed that the time constant B for the older group was significantly lower than for the young group (145.24± 80.28 vs. 239.23±136.59 sec.). A lower time constant value means a faster response to blood filling in the lower limbs and directly reflects decreased vessel elasticity. This time constant was lower in the older group. The results show increased vessel stiffness in old age and could lead to a non-invasive evaluating the cardiovascular system state.

Increased arterial stiffness is connected with vascular aging and cardiovascular diseases. Arterial stiffness correlates to Pulse Wave Velocity (PWV) which can be measured by the bioimpedance method.

Elevated arterial stiffness is a marker of vascular aging and is connected with increased mortality. Noninvasive measurement of arterial stiffness is based on the measurement of pulse wave velocity (PWV), where PWV correlates with arterial stiffness. PWV depends on blood pressure and other physiological conditions. The aim of our study was to measure and analyze the effect of changes in airway pressure to PWVs between the chest and limbs. Valsalva and Mueller maneuvers and spontaneous breathing were used. We measured 30 healthy, non-smoking subjects aged between 21 and 35 years. Simultaneous measurements of whole body impedance, blood pressure and ECG were taken in a supine position. The relative changes in PWV values (mean ± standard deviation) during the Valsalva maneuver were: 0.82 ± 0.11 (thigh); 0.87 ± 0.10 (calf); 0.64 ± 0.19 (arm); O. 75 ± 0.16 (forearm); during the Mueller maneuver they were: 0.92 ± 0.11 (thigh); 0.91±0.09 (calf); 0.76±0.19 (arm); 0.81±0.14 (forearm). PWVs were lower during maneuvers than during spontaneous breathing. Changes in PWV during breathing maneuvers were more reflected nearer to the chest. Our results show PWV reference values between various parts of the human body during changes in airway pressure demonstrated by the Valsalva and Mueller maneuvers.

Objectives: There is a large variability of exercise-inducedstroke volume behavior in healthy subjects. We sought to assessthe course of exercise-induced changes in stroke volume index(SVI) and other functional parameters in post-heart transplantpatients with heart failure and normal left ventricularejection fraction (HFNEF). Methods: Left ventricular functionand systemic hemodynamics were assessed at 40 s intervalsduring the exercise in 39 patients using simultaneous rightheart catheterization, bioimpedance, and echocardiography.Results: Twenty-six patients had exercise tolerance >/= 4.0METs (Group A), while 13 patients exhibited severely limitedexercise tolerance < 4 METs (Group B). Maximal SVI (maxSVI)achieved at any time during the exercise exceeded SVI at peakexercise (peakSVI) in 26 patients (67%). Both maxSVI and maxSVI(maxSVI minus SVI at rest) were significantly higher in Group Acompared to Group B patients (59 ml/m2 vs 41 ml/m 2, p < 0.01,and 21 ml/m2 vs 6 ml/m2, p < 0.01, respectively). With peakSVI,maxSVI, peakSVI, maxSVI and other variables evaluated, onlymaxSVI was independently associated with exercise tolerance.Conclusion: When assessing exercise-induced SVI changes inHFNEF patients, SVI should be followed during the course ofexercise and maximal SVI change from rest should always bedetermined.

Age, years 47 ± 3 35 ± 4 0.02 AH duration, years 14 ± 2 9 ± 3 N0.1 SBP, mm Hg 153 ± 5 140 ± 4 N0.1 DBP, mm Hg 91 ± 3 86 ± 4 N0.1 K+, mmol/l 4.5 ± 0.1 4.8 ± 0.2 N0.1 PRA, ng/ml/h 0.34 ± 0.05 1.78 ± 0.29 b0.01 PAC, pg/ml 219 ± 76 148 ± 43 N0.1 SBP24hr, mm Hg 141 ± 3 141 ± 3 N0.1 DBP24hr, mmHg 88 ± 2 83 ± 4 N0.1 EDV, mm 5.1 ± 0.1 5.2 ± 0.1 N0.1 WT, mm 1.07 ± 0.04 0.93 ± 0.03 0.09 RWT 0.42 ± 0.01 0.36 ± 0.02 0.03 LVMM, g 214 ± 17 178 ± 11 N0.1 ILVMM, g/m 109 ± 7 92 ± 6 N0.1 HR, bpm 66 ± 2 65 ± 4 N0.1 Effect of pacing rate on cardiac output and pulse wave velocity at rest L. Soukup , V. Vondra , I. Viscor , P. Jurak , J. Halamek b FNUSA-ICRC Brno Institute of Scientific Instruments AS CR

The methods and device for estimation of cardiac output and measurement of pulse wave velocity simultaneously is presented here. The beat-to-beat cardiac output as well as pulse wave velocity measurement is based on application of electrical impedance method on the thorax and calf. The results are demonstrated in a study of 24 subjects. The dependence of pulse wave velocity and cardiac output on heart rate during rest in patients with an implanted pacemaker was evaluated. The heart rate was changed by pacemaker programming while neither exercise nor drugs were applied. The most important result is that the pulse wave velocity, cardiac output and blood pressure do not depend significantly on heart rate, while the stroke volume is reciprocal proportionally to the heart rate.

The aim of the present study is to introduce ultra-high-frequency and high-dynamic-range 12-lead ECG measurements using an electromagnetically shielded environment (Faraday cage) and a battery-powered ECG monitor with sampling of 25 kHz and 24-bit resolution. To demonstrate its diagnostic contribution we present the results of 14 subjects - 7 healthy volunteers and 7 ischemic patients during short 15-minute resting supine recordings. Both groups of subjects have the same width of the regular QRS complex with no ST-segment abnormalities. Wide-band power envelope analysis up to 1000 Hz was applied on each QRS complex region. Artifact-free QRS complexes from approximately 500 beats were averaged with the R-wave maximum from lead V2 as a trigger. The power envelopes consist of narrow and compact shapes in all leads in healthy young volunteers. In ischemic patients, there is a significant expansion and splitting of frequency components and differentiation in measured leads. In this study, we have shown the ability of ultra-high-frequency and high-dynamic-range ECG measurement to detect heart muscle pathology.